materials-properties

Expert assistant for calculating materials properties from first-principles using ASE (Atomic Simulation Environment) and specialized packages. Comprehensive coverage of structure relaxation, surface energies, adsorption, reaction barriers, phonons, elastic constants, and thermodynamic modeling.

What This Skill Does

This skill enables Claude to help you:

• Perform structure relaxation and geometry optimization
• Calculate ground state properties (lattice constants, space groups)
• Compute surface energies for different facets
• Determine adsorption energies and preferred binding sites
• Find reaction barriers using nudged elastic band (NEB)
• Calculate vibrational frequencies and zero-point energies
• Compute phonon band structures and thermal properties
• Determine elastic constants and mechanical properties
• Build cluster expansion models for alloys
• Integrate DFT calculations with CALPHAD databases
• Calculate defect formation energies
• Analyze interfaces and grain boundaries
• Study magnetic properties
• Model thermal expansion
• Calculate electronic band structures

When to Use This Skill

Use this skill when you need to:

• Set up first-principles calculations with proper methodology
• Understand scientific methods for materials property calculations
• Get code examples with scientific citations
• Learn best practices for convergence testing
• Troubleshoot DFT calculations
• Integrate multiple computational tools (ASE, phonopy, elastic, icet, pycalphad)

Installation

Core Packages

# ASE and utilities
pip install ase spglib matplotlib

# Visualization (optional)
pip install ase-gui

Specialized Packages

# Phonon calculations
pip install phonopy

# Elastic constants
pip install elastic

# Cluster expansions
pip install icet

# CALPHAD integration
pip install pycalphad

DFT Calculators

# GPAW (requires compilation, conda recommended)
conda install -c conda-forge gpaw

# Or with pip (may require dependencies)
pip install gpaw

VASP: Requires separate license and installation. Use via ase.calculators.vasp.

Quantum ESPRESSO: Use via ase.calculators.espresso (requires QE installation).

Quick Start

1. Basic Structure Relaxation

from ase.build import bulk
from ase.optimize import BFGS
from ase.calculators.emt import EMT

# Create structure
atoms = bulk('Cu', 'fcc', a=3.6)

# Set calculator (EMT for fast testing)
atoms.calc = EMT()

# Optimize
opt = BFGS(atoms)
opt.run(fmax=0.01)

# Results
print(f"Energy: {atoms.get_potential_energy():.3f} eV")
print(f"Lattice: {atoms.cell.cellpar()[0]:.3f} Å")

2. Lattice Constant Determination

from ase.build import bulk
from ase.eos import calculate_eos

atoms = bulk('Cu', 'fcc', a=3.6)
atoms.calc = EMT()

eos = calculate_eos(atoms)
v, e, B = eos.fit()
a_opt = v**(1/3)
print(f"Optimal lattice constant: {a_opt:.3f} Å")
print(f"Bulk modulus: {B/1e9:.1f} GPa")

3. Surface Energy Calculation

from ase.build import bulk, fcc111

# Bulk energy per atom
bulk_atoms = bulk('Cu', 'fcc', a=3.6)
bulk_atoms.calc = EMT()
E_bulk = bulk_atoms.get_potential_energy() / len(bulk_atoms)

# Slab energy
slab = fcc111('Cu', size=(3,3,7), vacuum=10)
slab.calc = EMT()
E_slab = slab.get_potential_energy()

# Surface energy
N = len(slab)
A = slab.get_cell()[0,0] * slab.get_cell()[1,1]
gamma = (E_slab - N * E_bulk) / (2 * A)
print(f"Surface energy: {gamma*1000:.1f} meV/ų")

Skill Coverage

Core Capabilities

Structure Relaxation:

• Geometry optimization (force minimization)
• Unit cell optimization (stress relaxation)
• Constrained optimization
• Multiple optimizers (BFGS, FIRE, LBFGS)

Ground State Properties:

• Lattice constants and angles
• Space group determination
• Crystal structure identification
• Atomic positions
• Symmetry operations

Advanced Property Calculations (15 Subskills)

1. Surface Energy - Slab models, convergence testing
2. Adsorption Energy - Binding sites, coverage effects
3. Reaction Barriers (NEB) - Transition states, minimum energy paths
4. Vibrational Analysis - Normal modes, ZPE, IR/Raman
5. Phonons - Band structures, DOS, thermal properties (phonopy)
6. Elastic Constants - Full tensor, moduli, sound velocities (elastic)
7. Equation of State - Birch-Murnaghan, bulk modulus
8. Formation Energy - Phase stability, energy above hull
9. Cluster Expansions - Alloy ordering, Monte Carlo (icet)
10. CALPHAD - Phase diagrams, thermochemical data (pycalphad)
11. Defect Formation - Vacancies, interstitials, corrections
12. Interface Energy - Grain boundaries, adhesion
13. Magnetic Properties - Spin polarization, ordering
14. Thermal Expansion - Quasi-harmonic approximation
15. Electronic Structure - Band structure, DOS, band gaps

File Organization

materials-properties/
├── SKILL.md                          # Main skill instructions
├── README.md                         # This file
├── QUICK_REFERENCE.md                # Quick syntax guide
├── PLAN.md                          # Development plan with references
├── examples/
│   ├── basic_relaxation.py          # Simple optimization
│   ├── lattice_constant.py          # EOS calculation
│   ├── surface_energy.py            # Surface calculation
│   ├── adsorption_energy.py         # Adsorption workflow
│   ├── neb_barrier.py               # Reaction barrier
│   ├── phonon_calculation.py        # Phonon band structure
│   ├── elastic_constants.py         # Mechanical properties
│   ├── cluster_expansion.py         # Alloy modeling
│   └── complete_workflow.py         # Comprehensive example
├── references/
│   ├── surface_energy.md            # Detailed methodology
│   ├── adsorption_energy.md
│   ├── reaction_barriers.md
│   ├── vibrational_analysis.md
│   ├── phonons.md
│   ├── elastic_constants.md
│   ├── equation_of_state.md
│   ├── formation_energy.md
│   ├── cluster_expansion.md
│   ├── calphad.md
│   ├── defect_energy.md
│   ├── interface_energy.md
│   ├── magnetic_properties.md
│   ├── thermal_expansion.md
│   └── electronic_structure.md
└── workflows/
    ├── convergence_testing.md
    ├── best_practices.md
    └── calculator_comparison.md

Calculators Supported

EMT (Effective Medium Theory)

• Pros: Very fast, no setup required
• Cons: Limited elements (Cu, Ag, Au, Ni, Pd, Pt, Al, Pb, Fe)
• Use for: Workflow development, testing, teaching

GPAW

• Pros: Real DFT, well-documented, Python integration
• Cons: Requires compilation, slower than VASP
• Use for: Production calculations, method development

VASP

• Pros: Industry standard, very fast, well-validated
• Cons: Commercial license, less Python integration
• Use for: Large-scale production calculations

Quantum ESPRESSO

• Pros: Open source, well-established
• Cons: Input file based, less ASE integration
• Use for: Specific functionalities (DFPT, transport)

Scientific Methodology

All methods in this skill include:

• Proper formulas with clear definitions
• Scientific citations to original papers
• Convergence criteria and testing procedures
• Validation approaches against experiments/benchmarks
• Best practices from the literature
• Common pitfalls and how to avoid them

Key References

ASE:

• Larsen et al., J. Phys.: Condens. Matter 29, 273002 (2017)

DFT Foundations:

• Hohenberg & Kohn, Phys. Rev. 136, B864 (1964)
• Kohn & Sham, Phys. Rev. 140, A1133 (1965)

Textbook:

• Sholl & Steckel, Density Functional Theory: A Practical Introduction (Wiley, 2009)

See PLAN.md and individual reference files for complete citations.

Learning Path

Beginner

1. Basic structure relaxation
2. Lattice constant calculation
3. Equation of state
4. Space group identification

Intermediate

5. Surface energy calculations
6. Adsorption energy on surfaces
7. Vibrational analysis
8. Formation energies

Advanced

9. Nudged elastic band (reaction barriers)
10. Phonon band structures
11. Elastic constants
12. Cluster expansions
13. CALPHAD integration
14. Defect calculations

Common Use Cases

1. Optimize crystal structure: "Help me relax this CIF file and get the lattice constant"
2. Calculate surface properties: "Find the surface energy of the (111) facet of copper"
3. Adsorption study: "Determine where CO prefers to bind on a Pt surface"
4. Reaction mechanism: "Use NEB to find the barrier for H diffusion in Pd"
5. Thermal properties: "Calculate the phonon band structure and heat capacity"
6. Mechanical properties: "Compute the elastic constants and bulk modulus"
7. Phase stability: "Is this compound stable relative to its elements?"
8. Alloy modeling: "Build a cluster expansion for the Cu-Au system"

Best Practices

Convergence Testing

• Always test k-point convergence (typically < 1 meV/atom)
• Test plane-wave cutoff (if applicable)
• Test slab thickness for surfaces (5-9 layers typical)
• Test vacuum thickness (10-15 Å typical)
• Test supercell size for defects

Force Convergence

• Standard: fmax = 0.01-0.05 eV/Å
• Vibrations: fmax = 0.001 eV/Å
• Always check final forces

Documentation

• Record all calculation parameters
• Save trajectories for analysis
• Version control your scripts
• Document any unusual choices

Validation

• Compare to experimental values when available
• Check against benchmark calculations
• Verify convergence
• Use multiple functionals if uncertain

Troubleshooting

SCF not converging:

• Check for overlapping atoms
• Adjust mixing parameters
• Try different smearing
• Increase electronic temperature

Forces not converging:

• Check constraints
• Try different optimizer
• Verify calculator settings
• Increase max steps

Unexpected results:

• Verify structure is correct
• Check for symmetry breaking
• Test convergence parameters
• Compare to literature

Memory issues:

• Reduce k-points or cutoff
• Use smaller supercells
• Parallelize calculation
• Use more memory-efficient settings

Integration with Other Skills

• python-ase: Core ASE functionality
• materials-databases: Get structures from MP/AFLOW
• pymatgen: Structure manipulation
• fairchem: ML potentials for screening

Resources

• ASE Documentation: https://wiki.fysik.dtu.dk/ase/
• ASE Tutorials: https://wiki.fysik.dtu.dk/ase/tutorials/tutorials.html
• Phonopy: https://phonopy.github.io/phonopy/
• Elastic: https://elastic.readthedocs.io/
• ICET: https://icet.materialsmodeling.org/
• pycalphad: https://pycalphad.org/

Contributing

This skill is part of the skillz repository. See examples and references for detailed implementations of each method.

License

MIT License - Part of skillz project

Version Information

• Skill created for ASE 3.22+
• Python 3.8+
• Compatible with GPAW 24.x, phonopy 2.x